The species inhabits large, still or slow-flowing waters (Snow and Perrins 1998) and shows a preference for shallow water with adjacent deeper water for diving, and muddy substrates, marginal, emergent, floating or submergent vegetation. Habitats include eutrophic and mesotrophic (Taylor and van Perlo 1998) lakes, pools, ponds, reservoirs, barrages, gravel-pits, canals, drainage ditches, dykes, oxbow lakes (Taylor 1996), fish ponds (Musil 2006), creeks, rivers (Taylor 1996) and river deltas (Taylor and van Perlo 1998), as well as open marshes, freshwater meadows (Taylor and van Perlo 1998), flood-lands, salt-pans, clay-pans (Taylor 1996) and sewage ponds (Taylor and van Perlo 1998). It breeds from February to September.

The nest is a platform of vegetation that may be resting on the bottom of shallow water, floating or on a foundation of trampled plant matter in emergent vegetation. The species may also nest on artificial platforms, islands, rafts, tree stumps, tree forks (Taylor 1996) or in bushes up to 3 m above the water (Taylor and van Perlo 1998). This species is omnivorous, although its diet consists primarily of vegetable matter such as algae, the vegetative parts of aquatic and terrestrial plants, the seeds of waterweeds, sedges, water-lilies, grasses and cereal crops (Taylor 1996), clubmoss and aquatic fungi (Taylor and van Perlo 1998). Animal matter in its diet includes molluscs, adult and larval insects, worms, leeches, shrimps, spiders, small fish, fish eggs, frogs, birds and bird eggs, and small mammals (Taylor 1996). The species is mostly sedentary or a partial migrant, however in Fennoscandia and east of Czechia it is mostly migratory (Hagemeijer and Blair 1997).

Although the generation length for both EU and Europe regional assessments were calculated using the same methodology, new information arriving after the EU assessments were undertaken gave rise to an update in the generation lengths. This new information was then used for the Europe level assessments giving rise to a difference between the generation lengths used for the EU and Europe regions.

In Europe, this species breeds in almost every country in Europe, notably in Russia, the Netherlands, Ukraine, Germany, France and Romania.

Conservation Actions Underway
EU Birds Directive Annex II and III. The Mediterranean and Black Sea populations are on CMS Appendix II. The species is legally protected in Britain .

Conservation Actions Proposed
No conservation measures are currently needed for this species, although monitoring and research on the impacts of hunting, pollution and habitat alteration would help inform any future conservation measures.